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package com.ximsfei.stark.core;

import android.content.Context;
import android.content.pm.ApplicationInfo;
import android.content.res.Resources;
import android.text.TextUtils;

import com.ximsfei.stark.core.runtime.PatchLoader;
import com.ximsfei.stark.core.runtime.StarkConfig;
import com.ximsfei.stark.core.util.FileUtils;
import com.ximsfei.stark.core.util.ZipUtils;

import java.io.File;
import java.io.FileInputStream;
import java.io.FileOutputStream;
import java.io.InputStream;
import java.util.Enumeration;
import java.util.Properties;
import java.util.concurrent.ExecutorService;
import java.util.concurrent.Executors;
import java.util.zip.ZipEntry;
import java.util.zip.ZipFile;
import java.util.zip.ZipOutputStream;

import dalvik.system.DexClassLoader;
import io.sigpipe.jbsdiff.ui.FileUI;

public class Stark {
    private static final Stark sInstance = new Stark();
    private static final String PATCH_PATH = "stark-patch.jar";
    private static final String ARSC_FILE = "resources.arsc";
    private static final String ARSC_JDIFF = "resources.arsc.jdiff";
    private static final String ARSC_TMP = "resources.arsc.tmp";
    private static final String STARK_PROPERTIES = "stark.properties";
    private static final String KEY_STARK_PATCH_HASH = "stark.patch.hash";
    private static final String KEY_STARK_PATCH_TIME = "stark.patch.time";
    private Resources mResources;
    private boolean mPatchLoaded;
    private Context mAppContext;
    private ExecutorService mSingleExecutor = Executors.newSingleThreadExecutor();

    private Stark() {
    }

    public static Stark get() {
        return sInstance;
    }

    /**
     * If the patch file exists. The load method will loads the patch.
     *
     * @param context
     */
    public void load(Context context) {
        mAppContext = context.getApplicationContext() != null ? context.getApplicationContext() : context;
        File patch = getPatchFile(context);
        if (!patch.exists()) {
            return;
        }
        if (!checkPatchValid(patch)) {
            patch.delete();
            return;
        }
        DexClassLoader dexClassLoader = new DexClassLoader(patch.getAbsolutePath(),
                context.getCacheDir().getPath(), context.getCacheDir().getPath(),
                getClass().getClassLoader());
        try {
            Class<?> aClass = Class.forName("com.ximsfei.stark.core.runtime.StarkPatchLoaderImpl",
                    true, dexClassLoader);
            PatchLoader patchLoader = (PatchLoader) aClass.newInstance();
            mPatchLoaded = patchLoader.load();
        } catch (Exception e) {
            e.printStackTrace();
        }
    }

    /**
     * @param context
     * @param patchPath Patch's path in the file system.
     * @return
     */
    public boolean applyPatch(Context context, String patchPath) {
        File patchFile = new File(patchPath);
        if (!checkPatchUpdated(context, patchFile)) {
            patchFile.delete();
            return false;
        }
        File finalPatch = getPatchFile(context);
        File mergedFile = new File(patchFile.getParent(), "merged.apk");
        File installedFile = new File(context.getApplicationInfo().sourceDir);
        if (!patchFile.exists() || !installedFile.exists()) {
            return false;
        }
        try {
            ZipFile patchApk = new ZipFile(patchFile);
            ZipOutputStream zos = new ZipOutputStream(new FileOutputStream(mergedFile));
            ZipFile installedApk = new ZipFile(installedFile);
            Enumeration<? extends ZipEntry> entries = installedApk.entries();
            while (entries.hasMoreElements()) {
                ZipEntry entry = entries.nextElement();
                String name = entry.getName();
                ZipEntry patchEntry = patchApk.getEntry(name);
                if (patchEntry != null) {
                    ZipUtils.writeEntry(patchApk, zos, patchEntry);
                } else if (name.equals(ARSC_FILE)) {
                    ZipEntry jdiffEntry = patchApk.getEntry(ARSC_JDIFF);
                    if (jdiffEntry != null) {
                        File arsc = new File(patchFile.getParent(), ARSC_FILE);
                        FileUtils.copyFile(installedApk.getInputStream(entry), arsc);
                        File jdiff = new File(patchFile.getParent(), ARSC_JDIFF);
                        FileUtils.copyFile(patchApk.getInputStream(jdiffEntry), jdiff);
                        File arscTmp = new File(patchFile.getParent(), ARSC_TMP);
                        boolean merged = false;
                        try {
                            FileUI.patch(arsc, arscTmp, jdiff);
                            ZipEntry ze2 = new ZipEntry(entry.getName());
                            ze2.setTime(entry.getTime());
                            ze2.setComment(entry.getComment());
                            ze2.setExtra(entry.getExtra());
                            zos.putNextEntry(ze2);
                            FileInputStream is = new FileInputStream(arscTmp);
                            byte[] bytes = new byte[is.available()];
                            is.read(bytes);
                            zos.write(bytes);
                            merged = true;
                        } catch (Exception e) {
                            e.printStackTrace();
                        }
                        arsc.delete();
                        jdiff.delete();
                        arscTmp.delete();
                        if (!merged) {
                            ZipUtils.writeEntry(installedApk, zos, entry);
                        }
                    } else {
                        ZipUtils.writeEntry(installedApk, zos, entry);
                    }
                } else if (name.startsWith("assets/")
                        || name.startsWith("res/")
                        || name.equals("AndroidManifest.xml")) {
                    ZipUtils.writeEntry(installedApk, zos, entry);
                }
            }
            ZipEntry entry = patchApk.getEntry(STARK_PROPERTIES);
            ZipUtils.writeEntry(patchApk, zos, entry);
            patchApk.close();
            installedApk.close();
            zos.flush();
            zos.close();
            patchFile.delete();
            finalPatch.delete();
            FileUtils.copyFile(mergedFile, finalPatch);
            mergedFile.delete();
            return true;
        } catch (Exception e) {
            e.printStackTrace();
        }
        return false;
    }

    public void applyPatchAsync(Context context, String path) {
        applyPatchAsync(context, path, true);
    }

    /**
     * Apply patch asynchronous.
     *
     * @param context
     * @param path      Patch's path in the file system.
     * @param immediate If true. Take effect immediately after the patch is applied.
     */
    public void applyPatchAsync(final Context context, final String path, final boolean immediate) {
        mSingleExecutor.execute(new Runnable() {
            @Override
            public void run() {
                boolean applied = applyPatch(context, path);
                if (applied && immediate) {
                    load(context);
                }
            }
        });
    }

    public Resources getResources() {
        if (mResources != null) {
            return mResources;
        }
        if (mPatchLoaded && mAppContext != null) {
            loadResources(mAppContext);
        }
        return mResources;
    }

    private boolean loadResources(Context context) {
        try {
            File patch = getPatchFile(context);
            if (!patch.exists()) {
                return false;
            }
            if (!checkPatchValid(patch)) {
                patch.delete();
                return false;
            }
            ApplicationInfo info = context.getApplicationInfo();
            info.sourceDir = patch.getAbsolutePath();
            info.publicSourceDir = patch.getAbsolutePath();
            mResources = context.getPackageManager().getResourcesForApplication(info);
            return true;
        } catch (Exception e) {
            e.printStackTrace();
        }
        return false;
    }

    private boolean checkPatchValid(File patch) {
        try {
            ZipFile zip = new ZipFile(patch);
            ZipEntry entry = zip.getEntry(STARK_PROPERTIES);
            if (entry != null) {
                InputStream is = zip.getInputStream(entry);
                Properties stark = new Properties();
                stark.load(is);
                is.close();
                String hash = (String) stark.get(KEY_STARK_PATCH_HASH);
                if (!TextUtils.isEmpty(hash) && hash.equals(StarkConfig.BUILD_HASH)) {
                    return true;
                }
            }
        } catch (Exception e) {
            e.printStackTrace();
        }
        return false;
    }

    private boolean checkPatchUpdated(Context context, File patchFile) {
        try {
            ZipFile zip = new ZipFile(patchFile);
            ZipEntry entry = zip.getEntry(STARK_PROPERTIES);
            if (entry != null) {
                InputStream is = zip.getInputStream(entry);
                Properties stark = new Properties();
                stark.load(is);
                is.close();
                String hash = (String) stark.get(KEY_STARK_PATCH_HASH);
                if (!TextUtils.isEmpty(hash) && hash.equals(StarkConfig.BUILD_HASH)) {
                    long buildTime = Long.valueOf((String) stark.get(KEY_STARK_PATCH_TIME));
                    return buildTime > getPatchBuildTime(getPatchFile(context));
                }
            }
        } catch (Exception e) {
            e.printStackTrace();
        }
        return false;
    }

    private long getPatchBuildTime(File patch) {
        if (!patch.exists()) {
            return 0;
        }
        try {
            ZipFile zip = new ZipFile(patch);
            ZipEntry entry = zip.getEntry(STARK_PROPERTIES);
            if (entry != null) {
                InputStream is = zip.getInputStream(entry);
                Properties stark = new Properties();
                stark.load(is);
                is.close();
                return Long.valueOf((String) stark.get(KEY_STARK_PATCH_TIME));
            }
        } catch (Exception e) {
            e.printStackTrace();
        }
        return 0;
    }

    private File getPatchFile(Context context) {
        return new File(context.getCacheDir(), PATCH_PATH);
    }
}
